Bimetal plate to provide two different current ratings within frame of circuit breaker

Abstract

A circuit breaker having a frame comprises a bimetal plate having a longitudinal length wherein the bimetal plate is cut along the longitudinal length into a narrow section and a wider section both being parallel to each other such that the bimetal plate is configured to control when and how a trip mechanism of a trip unit activates. The circuit breaker comprises a heating element coupled to the bimetal plate to heat the narrow section and the wider section when a current goes through the heating element. The narrow section and the wider section of the bimetal plate to deflect differently when a same amount of heat is applied in a same amount of time to control when and how the trip mechanism activates such that to allow to have two different current ratings in the frame in that the bimetal plate allows to increment a current protection level from a lower current rating to a higher current rating.

What is claimed is: 
     
       1. A circuit breaker having a frame, the circuit breaker comprising:
 a trip unit including a trip mechanism having a trip bar with a tip; 
 a bimetal plate having a longitudinal length, wherein the bimetal plate is cut along the longitudinal length into a narrow section and a wider section both being parallel to each other such that the bimetal plate is configured to control when and how the trip mechanism of the trip unit activates and wherein the bimetal plate comprises a union of two different metal layers with different thermal expansion coefficients; 
 a heating element coupled to the bimetal plate to heat the narrow section and the wider section when a current goes through the heating element, wherein the narrow section and the wider section of the bimetal plate to deflect differently when a same amount of heat is applied in a same amount of time to control when and how the trip mechanism activates such that to allow to have two different current ratings in the frame in that the bimetal plate allows to increment a current protection level from a lower current rating to a higher current rating; and 
 a selector configured to rotate to a low current position and a high current position in order to pick the current protection level from two options, 
 wherein the trip bar, the tip, and the selector interact with the narrow section and the wider section of the bimetal plate, including the selector providing a lateral movement of the trip bar and the tip to change which bimetal section will contact the tip and displace the trip bar in the event of an over-current in order to provide the two different current ratings that increment from the lower current rating to the higher current rating by allowing only one of the narrow section and the wider section of the bimetal plate to contact the tip at a time and thereby allows only one current rating to be active at a given time. 
 
     
     
       2. The circuit breaker of  claim 1 , wherein at the low current position the bimetal plate is given heat by the heating element to deflect the wider section of the bimetal plate and make the wider section hit a tip of a trip bar of the trip mechanism of the circuit breaker such that the trip bar is displaced to open a latch which releases the trip mechanism. 
     
     
       3. The circuit breaker of  claim 1 , wherein at the high current position the bimetal plate is given heat by the heating element to deflect the narrow section of the bimetal plate and make the narrow section hit a tip of a trip bar of the trip mechanism of the circuit breaker such that the trip bar is displaced to open a latch which releases the trip mechanism. 
     
     
       4. The circuit breaker of  claim 1 , wherein the narrow section and the wider section of the bimetal plate having a width size ratio of 40:60 or 30:70 or 33:66 or 25:75. 
     
     
       5. The circuit breaker of  claim 1 , wherein the bimetal plate is shaped either in a rectangular shape or a trapezoid shape. 
     
     
       6. A method comprising:
 providing a trip unit including a trip mechanism having a trip bar with a tip; 
 providing a bimetal plate having a longitudinal length, wherein the bimetal plate is cut along the longitudinal length into a narrow section and a wider section both being parallel to each other such that the bimetal plate is configured to control when and how the trip mechanism of the trip unit activates and wherein the bimetal plate comprises a union of two different metal layers with different thermal expansion coefficients; 
 providing a heating element coupled to the bimetal plate to heat the narrow section and the wider section when a current goes through the heating element, wherein the narrow section and the wider section of the bimetal plate to deflect differently when a same amount of heat is applied in a same amount of time to control when and how the trip mechanism activates such that to allow to have two different current ratings in the frame in that the bimetal plate allows to increment a current protection level from a lower current rating to a higher current rating; and 
 providing a selector configured to rotate to a low current position and a high current position in order to pick the current protection level from two options, 
 wherein the trip bar, the tip, and the selector interact with the narrow section and the wider section of the bimetal plate, including the selector providing a lateral movement of the trip bar and the tip to change which bimetal section will contact the tip and displace the trip bar in the event of an over-current in order to provide the two different current ratings that increment from the lower current rating to the higher current rating by allowing only one of the narrow section and the wider section of the bimetal plate to contact the tip at a time and thereby allows only one current rating to be active at a given time. 
 
     
     
       7. The method of  claim 6 , wherein at the low current position the bimetal plate is given heat by the heating element to deflect the wider section of the bimetal plate and make the wider section hit a tip of a trip bar of the trip mechanism of the circuit breaker such that the trip bar is displaced to open a latch which releases the trip mechanism. 
     
     
       8. The method of  claim 6 , wherein at the high current position the bimetal plate is given heat by the heating element to deflect the narrow section of the bimetal plate and make the narrow section hit a tip of a trip bar of the trip mechanism of the circuit breaker such that the trip bar is displaced to open a latch which releases the trip mechanism. 
     
     
       9. The method of  claim 6 , wherein the narrow section and the wider section of the bimetal plate having a width size ratio of 40:60 or 30:70 or 33:66 or 25:75. 
     
     
       10. The method of  claim 6 , wherein the bimetal plate is shaped either in a rectangular shape or a trapezoid shape. 
     
     
       11. The circuit breaker of  claim 1 , wherein the bimetal plate comprises a first layer of 36% Nickel (Ni) and 64% Iron (Fe) with a low thermal expansion coefficient and a second layer of 22% Nickel (Ni), 3% Copper (Cu) and 75% Iron (Fe) with a high thermal expansion coefficient. 
     
     
       12. The circuit breaker of  claim 1 , wherein the bimetal plate comprises a first layer of 39% Nickel (Ni) and 61% Iron (Fe) with a low thermal expansion coefficient and a second layer of 22% Nickel (Ni), 3% Copper (Cu) and 75% Iron (Fe) with a high thermal expansion coefficient. 
     
     
       13. The circuit breaker of  claim 1 , wherein the bimetal plate comprises a first layer of 41% Nickel (Ni) and 58% Iron (Fe) with a low thermal expansion coefficient and a second layer of 22% Nickel (Ni), 3% Copper (Cu) and 75% Iron (Fe) with a high thermal expansion coefficient. 
     
     
       14. The method of  claim 6 , wherein the bimetal plate comprises a first layer of 36% Nickel (Ni) and 64% Iron (Fe) with a low thermal expansion coefficient and a second layer of 22% Nickel (Ni), 3% Copper (Cu) and 75% Iron (Fe) with a high thermal expansion coefficient. 
     
     
       15. The method of  claim 6 , wherein the bimetal plate comprises a first layer of 39% Nickel (Ni) and 61% Iron (Fe) with a low thermal expansion coefficient and a second layer of 22% Nickel (Ni), 3% Copper (Cu) and 75% Iron (Fe) with a high thermal expansion coefficient. 
     
     
       16. The method of  claim 6 , wherein the bimetal plate comprises a first layer of 41% Nickel (Ni) and 58% Iron (Fe) with a low thermal expansion coefficient and a second layer of 22% Nickel (Ni), 3% Copper (Cu) and 75% Iron (Fe) with a high thermal expansion coefficient.